The present invention relates to a piecing method and a piecing device for piecing a severed spun yarn on the winding package side and the sliver of a spinning machine for drafting a sliver and then winding to a winding package after spinning by a twisting device of such as a pneumatic type.
First, the structure of the relevant part of the spinning machine will be described with reference to FIG. 8.
Referring to FIG. 8, 10 is a draft device, and a back roller 11, a third roller 12, a middle roller 13 laid across an apron belt 14, and a front roller 15 are formed in this order from the upstream side. A sliver S from a first sliver guide 16 on the upstream side of the back roller 11 is drafted in a designated drafting ration between each roller and is supplied to a twisting device 17. A second sliver guide 16a is provided between the third roller 12 and the middle roller 13.
The twisting device 17 comprises a guide hole (fiber introducing hole) 20 for guiding a fiber bundle F drafted in the draft device 10 to a guide member 18 located opposing to the tip of a hollow guide shaft member 25 to be mentioned later on, a spinning nozzle 22 with a nozzle hole 21 for generating whirling air flow in the tip (spinning point) of the hollow guide shaft member 25 to be mentioned later on, a nozzle block 24 for holding the spinning nozzle 22 and forming an air room 23, the hollow guide shaft member 25 wherein the tip is provided facing the spinning nozzle 22, and a holding member 26 for closing the air room 23 by joining to the nozzle block 24, and which holds on the hollow guide shaft member 25, and separates the hollow guide shaft member 25 with respect to the spinning nozzle 22 during a yarn breakage.
The fiber bundle F drafted by the draft device 10 is guided along the guide member 18 from the guide hole 20, and then enters inside the hollow guide shaft member 25. The end of the fiber, the tip of which is released from the nip at the front roller 15 at the time being, is whirled by the whirling flow injected from the nozzle hole 21, is wound by reversing on the tip section of the hollow guide shaft member 25, and is sucked in while winding onto the fiber entering the hollow guide shaft member 25, to be a spun yarn Y like a true twist of which the most part of the fiber is to be a wrapping fiber. Moreover, the spun yarn Y is wound to the winding package (not shown in the drawings) by passing between a delivery roller 28 and a nip roller 29 contacting with the delivery roller 28 which compose the yarn feeding device on the downstream side of the twisting device 17.
Between the draft device 10 and the twisting device 17, an air shower tube 32 for blowing pressurized air to the sliver S during piecing, and a suction pipe 34 for holding the spun yarn at the winding package side and sucking the fiber blown off by the pressurized air from the air shower tube 32, are provided.
Next, the conventional piecing operation after the yarn breakage will be described in reference to FIG. 9 through FIG. 10.
When yarn breakage occurs, the back roller 11 and the third roller 12 which are a part of the draft rollers composing the draft device 10 are stopped, and the middle roller 13 and the front roller 15, which are on the downstream side are maintained in a driving state. At that time, the yarn feeding by the delivery roller 28 and the nip roller 29 is also maintained at a driving state for a while. As a result, as shown in FIG. 9, the sliver S is broken by the driving middle roller 13, and the sliver S stops with the tip section Sa positioned between the third roller 12 and the middle roller 13. At this time, the tip section Sa of the sliver S is held by the second sliver guide 16a. 
Following the stopping of a part of the draft rollers of the draft device 10, the driving (compressed air injection from the nozzle hole 21) of the twisting device 17 is stopped while the hollow guide shaft member 25 is transferred to a state in which it is separated from the nozzle block 24. Under such condition, preceding the piecing operation, the nip roller 29 is separated from the delivery roller 28 and the yarn feeding is stopped. Subsequently, the spun yarn Y at the winding package side is held by a yarn feeding roller 30 which comprises the yarn delivering member, and is fed back to the yarn discharging side of the twisting device 17 by being passed through the nip roller 29 and the delivery roller 28. Then, by the rotation of the yarn feeding roller 30, the spun yarn Y is fed toward the draft device 10, and in cooperation with the air flow (not shown in the drawings) toward the fiber bundle inlet of the guide hole 20, as a leading yarn Y (parent yarn), is passed through, in the opposite direction of the spinning direction inside the hollow guide shaft member 25.
Furthermore, by rotating the yarn feeding roller 30, the yarn tip of the leading yarn Y, projects from the guide hole 20 of the spinning nozzle 22 in cooperation with the air flow toward the fiber bundle inlet mentioned above, and the yarn tip of the leading yarn Y is held by being sucked by the suction pipe 34 provided between the spinning nozzle 22 and the front roller 15. Then, as shown in FIG. 10, the holding member 26 is joined with the nozzle block 24 again.
Then, the draft rollers (back roller 11 and third roller 12), which were stopped, are redriven, the sliver S is passed through the middle roller 13 and the front roller 15 and is delivered to the downstream side. At that time, the tip section of the sliver S is blown off by the pressurized air from the air shower tube 32 and is sucked and eliminated by the suction pipe 34 so that the guide hole 20 of the spinning nozzle 22 is not blocked.
Under the state in which the leading yarn (spun yarn) Y is held as in the manner stated above, the yarn feeding roller 30 is released from the yarn path, and starts running in the winding direction of the leading yarn Y by the nip roller 29 and the delivery roller 28. After redriving the injection of the whirling air flow from the nozzle hole 21, by stopping the injection of the pressurized air from the air shower tube 32, the fiber composing the sliver S is wound around the outer periphery of the leading yarn Y, the piecing is carried out and the spinning is recommenced.
However, there were problems in the piecing method and the piecing device of aforementioned conventional spinning machine as to be described in the following.
That is, since the distance between the air shower tube 32 and the sliver S is long, and the pressurized air hits the front roller 15 of the draft device 10, it was inefficient and there were cases in which the joint is bunched up together without the fiber, of which the fiber length is long and unlikely to be blown off to be eliminated completely.
Moreover, after stopping the injection of the pressurized air from the air shower tube 32, since the fiber amount of the sliver S, which is to enter the guide hole 20 of the spinning nozzle 22 for piecing, is the normal fiber amount; in other words, a fiber amount that is the same as the leading yarn Y, the joint thickness will be theoretically 2 times that of the leading yarn Y in cross section, and in diameter, 1.4 times.
These were the yarn defects, and there was a problem in that the quality of the spun yarn as a product decreases.
The object of the present invention is to solve the problems mentioned above, and to provide a piecing method and a piecing device of a spinning machine capable of blowing off the sliver effectively during piecing and controlling the joint thickness.
The present invention to achieve the object mentioned above, relates to a piecing method for blowing pressurized air to a sliver and sucking and guiding by a suction pipe provided between a twisting device and a draft device to carry out piecing to a leading yarn fed back to the twisting device and the sliver from the draft device, wherein the pressurized air is made to be blown in an opposing direction toward the sliver from the periphery of a spinning nozzle of the twisting device.
If constructed in accordance with the invention, the pressurized air can be blown from a position close to the sliver, and since there are no obstacles for the blowing, the sliver can be blown off efficiently.
Moreover, the pressurized air can be set to be weaker than the suction force of the spinning nozzle of the twisting device during piecing, and the joint thickness achieved by the piecing can be controlled to be a desired thickness by selecting the blowing time of the pressurized air.
Accordingly, the joint thickness can be controlled by blowing off and eliminating a part of the fiber of the sliver to enter the guide hole of the spinning nozzle.
Moreover, the present invention relates to a piecing method for blowing pressurized air to a sliver and sucking and guiding by a suction pipe provided between a twisting device and a draft device to carry out piecing of a leading yarn fed back to the twisting device and the sliver from the draft device, wherein an air nozzle for blowing pressurized air in a direction opposing the sliver delivered from the draft device is provided around a spinning nozzle of the twisting device.